import time
import collections
import select
import threading
from Logger import Logger

GPIOType = collections.namedtuple("GPIOType", [ "io", "number", "name", "inverted", "filename" ])

_log = Logger("IOAccess")

class InputPoller(threading.Thread):
    def __init__(self, inputs, callback):
        threading.Thread.__init__(self)
        self._inputs = inputs
        self._callback = callback
        self._files = { gpio.name: open(gpio.filename, "r") for gpio in self._inputs }
        self._pollobj = select.poll()
        for (name, f) in self._files.items():
            self._pollobj.register(f.fileno(), select.POLLPRI)

    def _getall(self):
        values = { }
        for gpio in self._inputs:
            f = self._files[gpio.name]
            f.seek(0)
            data = f.read()[:-1]
            data = (data == "1")
            data ^= gpio.inverted
            values[gpio.name] = data
        return values

    def run(self):
        while True:
            pollresult = self._pollobj.poll(1000)
            if len(pollresult) > 0:
                self._callback(self._getall())

class IOAccess():
    def __init__(self):
        self._gpios = { }
        self._lastvalues = { }

    def addinput(self, gpiono, name, inverted = False):
        self._gpios[name] = GPIOType(io = "in", number = gpiono, name = name, inverted = inverted, filename = IOAccess._gpiofilename(gpiono))

    def addoutput(self, gpiono, name, inverted = False):
        self._gpios[name] = GPIOType(io = "out", number = gpiono, name = name, inverted = inverted, filename = IOAccess._gpiofilename(gpiono))

    def _gpiofilename(gpiono):
        filename = "/sys/class/gpio/gpio%d/value" % (gpiono)
        return filename

    def listen(self, listener):
        inputs = { gpio for gpio in self._gpios.values() if gpio.io == "in" }
        thread = InputPoller(inputs, listener)
        thread.start()

    def setoutput(self, gpio, value):
        if value:
            writestr = "1"
        else:
            writestr = "0"
        f = open(gpio.filename, "w")
        print(writestr, file = f)
        f.close()

    def pulse(self, gpioname, length = 0.01):
        gpio = self._gpios[gpioname]
        assert(gpio.io == "out")
        _log.log("Pulse %s len %.3f sec" % (str(gpio), length))
        t0 = time.time()
        self.setoutput(gpio, not gpio.inverted)
        time.sleep(length)
        self.setoutput(gpio, gpio.inverted)
        t1 = time.time()
        _log.log("Actual pulse len %.3f sec (%+.3f sec)" % (t1 - t0, (t1 - t0) - length))

    def multipulse(self, gpioname, ontime, offtime, count):
        for i in range(count):
            self.pulse(gpioname, ontime)
            time.sleep(offtime)

if __name__ == "__main__":
    import sys
    ioa = IOAccess()
    ioa.addinput(21, "BtnUp", True)
    ioa.addinput(4, "BtnDown", True)
    ioa.addinput(17, "BtnRight", True)
    ioa.addinput(22, "BtnLeft", True)
    ioa.addoutput(23, "AudioSilent", False)
    ioa.addoutput(24, "AudioLouder", False)
#   ioa.pulse(sys.argv[1], float(sys.argv[2]))
    def listener(states):
        print(states)

    ioa.listen(listener)
    while True:
        time.sleep(1)